Sources of Symbols

Classrooms and Clip Art

Elementary schools and clip art have reduced the drawing of some tangible
objects to a few simple conventions. As long as you follow those conventions,
the image will be recognized. See also Cartoons and
Corporate Logotypes

Simplified or Standardized Drawing:

Two things to notice:

Standardized drawings often include characteristics that do not necessarily
appear on every specimen of this object.

Some of these drawings highlight the one or two most distinctive
characteristics of the object at the expense of more commonplace
characteristics.

Angel (OK, technically, an angel isn't a "tangible object", but
that proves my point. Even though no one has seen one, we all know how to draw
one -- with wings and a halo.)

Apple (An apple is generically round when viewed from the outside, so we
draw the shape of its cross-section instead. And include a stem.)